It's fine to idle it for a whole tank for the first time. On many engines it is recommended. High idle will cause the truck to start driving itself. If it takes 8-10 seconds to shut off via the fuel tube, then it's running pretty rich, which is good for break in.

I never used after run oil either. I've gone to like 3 gallons on my current engine, and don't have any problems. Still makes awesome power, even more than when it was new.